POJ2083-Fractal

http://poj.org/problem?id=2083

递归，分治思想。

#include<stdio.h>
char box[730][730]={"",""};
void drawFractalBox(int n,int x,int y)
{
    int i=n,c=1;
    while(--i)
       c=c*3;
    if(c==1)
    {
        box[x][y]='X'; 
        return;
    }
    else
    {
        drawFractalBox(n-1,x,y); 
        drawFractalBox(n-1,x,(c*2)/3+y); 
        drawFractalBox(n-1,c/3+x,c/3+y); 
        drawFractalBox(n-1,(c*2)/3+x,y); 
        drawFractalBox(n-1,(2*c)/3+x,y+(2*c)/3); 
    }
}
int main(void)
{
    int i,j,n,num,t;
    while(scanf("%d",&n),n!=-1) 
    {
        num=1;
        t=n;
        while(--t)
           num=num*3;
        for(i=1;i<=num;i++)
            for(j=1;j<=num;j++)
                box[i][j]=' '; 
        drawFractalBox(n,1,1);
        for(i=1;i<=num;i++)
        {
            for(j=1;j<=num;j++)
               printf("%c",box[i][j]);
            printf("\n");
        }
        printf("-\n");
    }
    return 0;
}